WEDNESDAY, Feb. 10 (HealthDay News) -- Postmenopausal women with breast cancer have worse cognitive function after treatment with tamoxifen but not exemestane, according to a study published online Feb. 8 in the Journal of Clinical Oncology.

Christina M. Schilder, from the Netherlands Cancer Institute in Amsterdam, and colleagues examined cognitive function in 80 postmenopausal breast cancer patients treated with tamoxifen, 99 postmenopausal breast cancer patients treated with exemestane, and 120 healthy women who were participating in a randomized clinical trial. The patients did not receive chemotherapy.

After one year of treatment, the researchers found that cognitive function in the exemestane group was similar to healthy women. In contrast, the tamoxifen group had significantly lower verbal memory and executive function compared with healthy women, and significantly worse information processing speed compared with the exemestane group. All three groups had similar visual memory, working memory, verbal fluency, and reaction and motor speeds.

"In conclusion, our results suggest that compared with healthy controls, exemestane did not result in the same cognitive decline over time that was seen in patients with breast cancer taking tamoxifen," Schilder and colleagues write. "Although the impact of the observed cognitive effects on daily life of patients has yet to be determined, intact cognitive functioning is known to be an important precondition for independent living and well-being."

The study was supported by an independent research grant from Pfizer; Schilder reported financial ties to Pfizer.